THE INFLUENCE OF RIVER DISCHARGE AND TIDE ON RESIDENCE TIME IN BERAU DELTA IN JUNE – NOVEMBER 2007

• Main Author: Ilham, Muhammad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/62663
• Institution: Institut Teknologi Bandung

Residence time is a transportation time scale parameter that can be used as a reference to understand chemical and biological processes in coastal area. This study aims to identify the influence of river discharge and tide on the residence time in the Berau Delta from June to November 2007. In this study, the simulation of the hydrodynamic model and trajectory model was using Delft3D-FLOW. There are two model scenarios based on the initial tidal conditions of the trajectory simulation, the Pu Scenario (the start of the simulation during the spring tide) and the Pe Scenario (the start of the simulation during the neap tide). Then the Pu Scenario and Pe Scenario are divided into eight scenarios based on river discharge (!! = 0 m3/s; !" = 245.3 – 1379.4 m3/s; !# = 223.9 – 813.3 m3/s; !$ = 232.9 – 1105.9 m3/s; !% = 223.9 – 1379.4 m3/s; !"& = 649.99 m3/s; !#& = 538.21m3/s; !$& = 598.57 m3/s) with !! Scenario is no river discharge, !", !#, !$ Scenario is the variation of daily river discharge, !% Scenario represents the river discharge during June to November 2007, and !"&, !#&, !$& Scenario is two months averaged the river discharge. The verification of tidal elevation and tidal components between model and data observation are good with RMSE range between 0.16 to 0.29 m, MAPE value is 3.74 to 11.30 % and correlation coefficient above 0.9. In the Pu Scenario and the Pe Scenario, the residence time increases from the mouth of the delta to inside the delta. Variations in river discharge intensely affect the residence time for the Pu Scenario and the Pe Scenario. Simulation with the highest variation of average river discharge !"& (river discharge 649.99 m3/s) have the lowest residence time, whereas the simulation with zero river discharge (!! = 0 m3/s) have the highest residence time. In the Pu Scenario, the residence time obtained is 8.36 to 13.41 days, smaller than the Pe Scenario which has a residence time of 9.81 to 16.62 days. However, in !$ river discharge, the residence time value in the Pu Scenario is greater than the Pe Scenario with a difference of 0.15 days. In the Pu4 Scenario, the number of particles that came out from the delta reached 97.183% with a residence time value of 13.41 days, while in the Pe4 Scenario, the number of particles that came out from the delta reached 96.40% with a residence time value of 16.62 days.